A microfiche appendix, Appendix A, is included of a computer program listing. The total number of microfiche is 6. The total number of frames is 186. A second microfiche appendix, Appendix B, is also included of schematic diagrams. The total number of microfiche is 1 and the total number of frames is 23.
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
Generally, this invention relates to revenue meters of the type used by energy suppliers to accurately measure electrical energy delivered to consumers. More particularly, this invention relates to improved interfacing of the revenue meters.
In a typical electrical distribution system, an electrical supplier or utility company generates electrical energy and distributes the electrical energy to consumers via a power distribution network. The power distribution network is the network of electrical distribution wires which link the electrical supplier to its consumers. At the consumer""s facility, there will typically be an electrical energy meter (revenue meter) connected between the consumer and the power distribution network to measure the consumer""s electrical demand. The revenue meter is an electrical energy measurement device which accurately measures the amount of electrical energy flowing to the consumer from the supplier. The amount of electrical energy measured by the meter is then used to determine the amount required to compensate the energy supplier.
To provide user input to the revenue meter, known meters typically utilize cumbersome keys or buttons located within a sealed cover of the revenue meter, or keys which are accessible from the outside but are sealed and cannot be activated without removing the seal. In both cases, at least one security seal is installed to prevent or indicate unauthorized access. Thus, the seal must be replaced every time the meter is accessed.
A problem exists when keys are added to the cover to access the revenue meter since tolerances in both the manufactured parts and the assembly process can cause an internal structure of the assembled revenue meter to misalign with the cover, for example, lean and twist with relation to the cover. Yet, it is important to line up the keys on the cover with the appropriate buttons on the revenue meter.
Another problem stems from the fact that typical socket based revenue electricity meters provide Input and Output (I/O) ports. These ports can be analog or digital, inputs or outputs. Analog inputs are capable of measuring a 4-20 mA input signal which may indicate, for example, temperature from an external transducer. Moreover, analog outputs typically generate 4-20 mA outputs that indicate, for example, power being measured by the meter. Digital inputs typically connect to external contacts which may indicate, for example, the position of a switch in the substation. Moreover, digital outputs may be solid state relays capable of switching small loads on and off.
Known revenue meters typically use two methods of obtaining the I/O signals for the I/O from the revenue meter. The first method utilizes individual wires for each I/O port. The second method uses an industry standard communications protocol over, for instance, twisted pair communications wiring to communicate with an external third party device which provides the I/O ports.
On the one hand, since ANSI standard revenue metering sockets were not designed with I/O in mind, bringing I/O ports out of the meter on individual wires presents numerous problems. First, no provision exists for rendering the ports on terminals since the standard socket does not provide any. Therefore, the ports must exit the meter on individual wires. All signals, except voltage and current, must exit through a small port on the back of the socket. The amount of space available for this port is limited, therefore the number and size of wires that can exit the device is limited. Yet, known revenue meters may be required to provide a bundle of cables with a large amount of conductors to accommodate I/O and communication signals.
In addition, since the I/O circuitry is located inside the revenue meter, the revenue meter""s size must increase to accommodate the circuitry. Additionally, the revenue meter must dissipate the additional heat generated by the I/O circuitry. Moreover, when an installer installs the device, they are faced with sorting out a large bundle of wires, typically by color coding, which is prone to error. The bundle of conductors are cumbersome to handle, and the area to access and connect the conductors is often limited. Finally, the I/O signal wires must be extended and routed to devices that may be located a great distance away from where the revenue meter is mounted.
On the other hand, using an industry standard communications protocol to communicate from the meter to an external I/O device solves many of the problems that accompany the internal I/O, but creates additional problems. Known standard communications interfaces typically do not provide a way to timestamp the absolute time that the input state was recorded, which is an important feature to various functions of the revenue meter. Even when this capability is provided, there is typically no way to ensure that the absolute time reference of the external I/O device and the revenue meter are the same. In addition, standard communications interfaces are typically bus architectures. Therefore, transferring I/O information from the external I/O device to and from the meter may be delayed by other devices using the bus. Also, known external I/O devices are often complicated to configure. In addition, standard external I/O devices must have dedicated power supplies which means additional wiring must be installed.
Thus, there is a need for an improved revenue meter that provides easily accessible and easy to use interfaces. This includes both a front panel, as well as I/O and communications connections. In addition, there is a need for an improved revenue meter with an I/O and communications interface that is located separate from the revenue meter. In addition, there is a need for an external I/O device that is easy for the user to configure, hence reducing installation time. Moreover, there is a need for an I/O and communications interface that is expandable and not limited to the number of conductors leaving the revenue meter.
Such needs are met or exceeded by the present interfaces for a revenue meter. In general, the revenue meter of the present invention provides easily accessible and easy to use interfaces that include a front panel keypad and I/O and communications connections. The keypad allows a user to interact with the meter without requiring a breach to a security seal. Moreover, the external I/O and communication interface is expandable and allows easy connection to and detachment from the revenue meter.
More specifically, the preferred embodiment of the present invention revenue meter includes electronics for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit. A meter cover encloses the revenue meter. A keypad is located on the meter cover, and connects to the revenue meter to access the revenue meter without requiring removal of the meter cover.